Search

In this article, a multivariate analysis of the parameters determining the transport and fate of selected heavy metals in the water - bottom sediment interface was carried out. The studies were carried out in the summer season of 2019 at Nielisz Reservoir (southeastern Poland, Lublin Voivodeship). Finally, a previously unknown factor related to the quality of organic matter was identified. Autochthonous organic matter was shown to promote the accumulation of the studied heavy metals. To date, the significance of the origin of organic matter in the context of the transport and fate of heavy metals in retention reservoirs has rarely been reported in the scientific literature. More than that, this factor was not considered an important component in the process of heavy metal deposition in bottom sediments. However, it turns out that not only the quantity of organic matter, but also its quality plays an important role in the circulation of heavy metals in retention reservoir ecosystems. It was found that autochthonous organic matter promotes the accumulation of the studied heavy metals. It can be assumed that, in a sense, it plays the role of a catenary ("hub") controlling the fate of heavy metals in the water-sediment system. It has also been conjectured that, in a sense, OM S may reflect the potential for heavy metal assimilation by aquatic vascular plants (mainly of the C3 group). Plants with a photosynthetic pathway similar to the C3 group generally have a much lower enrichment in the 13 C isotope (δ 13 C from -38‰ to -22‰). In our case, the lowest δ 13 C-TOC S value was -24.05‰, and the average for the whole reservoir was -21.53‰. In addition, it was observed that quantitative changes in the isotopic composition of total organic carbon δ 13 C-TOC S , corresponded with changes in the content of the heavy metals studied in entrapped sediments., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The significance of suspended sediment in the context of nutrient cycling and distribution in reservoirs is rarely reported in the scientific literature. What's more, suspended sediment (SS) have so far not been taken into account as a potential factor amplifying the degrading effects of nutrients on the functioning of reservoirs. In the experiment described here, the variability of SS concentrations and the content of total nitrogen (TN), total phosphorus (TP), total organic carbon (TOC) and organic matter (OM) were investigated to determine the potential and determinants of SS in the process of migration of these substances at the water-sediment interface in retention reservoirs. The results showed that SS significantly manipulate the distribution of values of total phosphorus and total organic carbon contained in bottom sediment. It was confirmed that the circulation and distribution of selected nutrients in reservoirs is closely related to suspended sediment. Thus, it was proven that SS significantly affect the quality of deposited sediment. Finally, it was concluded that suspended sediment in the water of reservoirs forms a kind of micro-ecosystem, in which it plays a hitherto undiscovered role of a catenary (hub) consolidating a number of phenomena and processes occurring between individual components in the water-bottom sediment system., (© 2024. The Author(s).)

It is crucial to have a comprehensive understanding of the process by which suspended sediment (SS) in water is aggregated and deposited to ensure the proper use and management of storage reservoirs. The present study was an investigation into the varied granulometric composition of accumulated sediment, as well as an examination of the amounts of organic matter present and its origins. This study aimed to determine what underpins the process of aggregation of sediment suspended in reservoir water. The results of the study, as also analysed using multivariate statistics, reveal a process of sediment aggregation dependent not only on the amount of organic matter but also on its origin. Greater production of autochthonous organic matter was shown to be associated with an intensified process of suspended sediment flocculation, confirming that the metabolism of a reservoirs' aquatic organisms influences the granulometric composition of suspended sediment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

While temperate reservoirs can be a significant source of atmospheric methane (CH 4 ), knowledge of the role they play in global emissions of the gas remains limited in line with extreme temporal and spatial variability noted both within and between reservoirs. There is also still no clear identification of the environmental factors influencing the emission of this gas to the atmosphere. This article presents the results of research into the influence of sedimenting matter on CH 4 emission from the surface of different zones of reservoirs. The research were conducted in 2018-2019 within Maziarnia and Nielisz Reservoirs - two artificial bodies of water of eutrophic status both located in SE Poland. Their diffusive CH 4 fluxes at the water-air interface were measured using the "static chamber" method, while sediment traps monitored the rate of accumulation of sedimenting matter in bottom sediments (U S ). The CH 4 fluxes noted at the reservoirs proved highly variable, both temporally and spatially, ranging from 0.02 to over 2500 mmol/m 2 ·d. Determined accumulation indexes were in turn in the 13.61-618.49 g/m 2 ·d range. Nevertheless, CH 4 flux was found to correlate significantly with sedimentation index (U S ), with highest observed values for both reservoirs noted in river zone, while the lowest characterise the lacustrine zone. On this basis, it was hypothesised that sedimentation index may prove a useful tool in estimating CH 4 emissions from reservoirs, with the reverse relationship also likely to apply. Furthermore, the key factor found to be responsible for the aforementioned temporal and spatial variations in CH 4 emissions is primary production, whose subsequent sedimentation supplies sediments with easily-degradable organic matter. The results presented here contribute to an understanding of environmental factors that may influence spatial variation in CH 4 production and can be useful to serve determinate of potential methods by which to reduce emissions this gas from managed systems such as reservoirs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

This paper presents the results of research into pathways leading to the production of methane (CH4) and carbon dioxide (CO2) in sediments of two eutrophic reservoirs (Maziarnia and Nielisz), located in south-eastern Poland. In seeking to identify the pathways in question, use was made of analysis of stable carbon isotopes in CH4 and CO2 dissolved in pore water. This determined that CH4 is mainly produced through acetate fermentation, though the hydrogenotrophic methanogenic process may also be of importance, especially in deeper layers of sediments. Both the presence of autochthonous organic matter and increased pH values are shown to favour acetate fermentation. In turn, methanogenesis in sediments is assessed as capable of accounting for the generation of a considerable amount of CO2. Indeed, the role of methanogenesis in CO2 production is increasingly important further down in the layers of sediment, where allochthonous organic matter is predominant., Competing Interests: The authors have declared that no competing interests exist.

Studies concerning the emission of carbon dioxide (CO 2 ) were carried out in 2009-2012 for six reservoirs located in four provinces of south-eastern Poland. The CO 2 flux across the water-air interface was measured using the "static chamber" method. The measured fluxes of CO 2 (FCO 2 ) ranged from -30.64 to 183.78mmol/m 2 /day, and the average values varied in the range from -3.52 to 82.11mmol/m 2 /day. In most of the cases, emission of CO 2 to the atmosphere was observed. The obtained values of CO 2 fluxes were comparable to values typical for other temperate reservoirs. Analysis of the influence of selected environmental factors on the FCO 2 showed that it depends on parameters characterizing both the sediments and surface water. The CO 2 flux at the water-air interface was positively correlated with parameters of bottom sediments such as porosity, content of organic carbon and total nitrogen; and negatively with pH value and δ 13 C of organic carbon. In the case of the parameters characterizing surface water, positive dependences on the concentrations of nitrate and total nitrogen, and negative relationships with water temperature and chlorophyll a concentrations, were found., (Copyright © 2016. Published by Elsevier B.V.)

The estimated diffusion fluxes of methane (CH 4 ) and carbon dioxide (CO 2 ) at the sediment-water interface in the Rzeszów Reservoir in southeastern Poland are presented. The relevant studies were conducted during 2009, 2010, and 2011. Calculated fluxes ranged from 0.01 to 2.19 mmol m -2  day -1 and from 0.36 to 45.33 mmol m -2  day -1 for methane and carbon dioxide, respectively. While the values for calculated diffusion fluxes of methane are comparable with those reported for other eutrophic reservoirs, much higher values were obtained here for carbon dioxide. The resulting values of δ 13 C-CH 4 and the fractionation coefficients between methane and carbon dioxide (αCH 4 -CO 2 ) suggest that methane in the sediment of the Rzeszów Reservoir is produced by acetate fermentation, while the hydrogenotrophic methanogenic process is of successively greater importance with increasing depth. In the top layer of the sediment, 24-72 % of CO 2 came from methanogenesis, while the contribution made by the degradation of organic matter by methanogenesis to CO 2 was greater in the deeper layer.

A reference study on both the nitrogen content in waters and nitrogen and oxygen isotopic signatures characterising nitrate from different sources was conducted within the San River catchment area. Three kinds of catchments were studied: (1) forested and uncultivated; (2) artificially fertilised with nitrate; and (3) fertilised with manure and sewage. Moreover, atmospheric water was studied. The obtained values were found to be similar to others in the literature, with the exception of nitrate from the atmosphere, in regard to which influence reflecting the local conditions was to be noted. The isotopic signature of nitrate in the studied water results from the biogeochemical transformation of nitrogen compounds rather than from the mixing of different sources. The obtained results were statistically distinct and can be used as end-member values in further modelling studies connected with the management of nitrate in river waters, especially under middle-eastern European conditions.

Dissimilatory nitrate reduction to ammonium was examined in the bottom sediment of selected reservoirs. In vitro measurements of DNRA rates were made with undisturbed sediment cores, using an 15N stable isotope technique. 15NH4+ analysis was conducted using a C and N Elemental Analyzer, model EA 1112 (ThermoQuest) on line with IRMS (DELTA+ Finnigan). Multiple regression was applied to examine the combined influence of selected abiotic factors on the rate of the DNRA process occurring in the bottom sediment of Poland's Rzeszów and Solina Reservoirs. The resulting models revealed that temperature, the concentration of nitrate in overlying water, and organic matter (OM) content in bottom sediment have a significant influence on DNRA rates in the bottom sediment of the Rzeszów Reservoir, while temperature and OM content in bottom sediments have a significant influence on the rate in the Solina Reservoir. The correctness of the model was verified using the Fisher - Snedecor test at a significance level of p < 0.001. The importance of DNRA in comparison with denitrification was also analysed.